Location: Horticultural Crops Research2013 Annual Report
1a. Objectives (from AD-416):
Objective 1: Determine effects of water management on wine grape productivity and fruit maturity. Objective 2: Integrate the development and use of analytical methods for the evaluation of phenolic compounds and other chemical indicators of quality in fruit, fruit products, and wine. Objective 3: Determine effects of vineyard and vine microclimate on fruit development, vine productivity, and fruit quality, particularly phenolic compounds.
1b. Approach (from AD-416):
Our fundamental approach for conducting the proposed research is based on interdisciplinary work toward grape production systems and connecting production practices to the quality of the harvested fruit or value-added fruit products. Although each team member is responsible for a distinct experimental focus, overall goals and responsibilities of the contributors overlap because the interactions among system processes and properties transcend disciplines.
3. Progress Report:
A computer model was developed to alert grape growers to critically cold temperatures in winter that could damage their grapevines. This model was posted on a publicly accessible website operated by the cooperator, Washington State University. The model allowed growers to select a weather station closest to their own vineyards rather than from a central location at some distance from their farm, which was the main limiting factor of the previously available information. Because temperatures are different at different locations, it is important for the grower to know how cold it is expected to be overnight at his or her specific location. Damage to grapevines from excessively cold temperatures reduces grape yield in the following year. Temperature and sunlight affect the quality of grapes, which affects market price. Growers must manage grapevines to avoid excessive sunlight on the fruit which leads to excessive temperature; both are deleterious. We determined the negative effects of extreme high fruit temperatures. We also determined the effect of the range of temperature between day and night on the chemical compounds that impart astringency to wine. Wine grape producers in warm climates (the majority of the US industry) are applying these results to change the management of the shoots and leaves of the grapevines to provide some shade to the fruit during the hottest part of the day. During the past 5 years, selected preparation methods were employed for analyses on the relationship between agricultural practices (i.e., cover cropping and tilling, canopy leaf removal, vine nutrition), biotic stresses (i.e., virus status), and genotypes (i.e., black raspberry, lingonberry, cranberry, basil, potato) and their affect on fruit primary and secondary metabolites (i.e., proanthocyanidins, anthocyanidins, sugars, organic acids). In the new project plan (2013-2018), ARS scientists in Parma, Idaho, and Prosser, Washington, propose to refine agricultural management practices to be used by growers to improve fruit and fruit product quality, and to sustain a competitive US agricultural economy. An objective of this 5-year project was to enhance our understanding of how irrigation practices influence wine grape productivity and berry maturity. We identified influences of irrigation amount on vine canopy density, volatile compounds in grape and wine, and wine sensory attributes. We found an increased incidence of high temperature stress in deficit-irrigated vines grown under arid conditions with high solar radiation, particularly in west-exposed berries. In 2012 we completed a multi-year study showing that foliar application of a white, kaolin-based particle film to the vine canopy increased reflectance of solar radiation from leaf and berry surfaces and beneficially reduced surface temperatures. In 2012, we collected the second year of a multi-year study on the influence of irrigation amount and frequency on vine water status and productivity. Our replacement project will continue to study irrigation practices and techniques that optimize productivity and fruit quality and mitigate the impact of drought and cold.